Week Ten- one more to go!

August 13th, 2012

So technically I’ve entered the realm of my final week here, but it’s been pretty hectic so I never had a chance to write a blog for last week! On Monday I had the pleasure of trying to get an abstract in for internal review here at the USGS. I had had two people review it over the weekend (since the deadline was noon on Monday), including my advisor, but then I was informed at 11:50am while checking through the abstract one last time with my advisor, that neither he nor my other reviewer could actually review it because they were also co-authors on the abstract (which had totally slipped my mind given that this was just internal review). So I began wildly searching the office for two new people to look at it (which was surprisingly difficult given that half the people were busy reviewing someone else’s abstract, and the other half were out at lunch). But finally I was able to get it to not two, but three reviewers who all had it back to me by mid afternoon. No one seemed particularly stressed out about the noon deadline, so that helped calm me down while I made corrections and then went through it one last time with my advisor. Finally, by the very end of the day I was able to give it in for internal review. They came back and approved it on Wednesday so I was able to submit it to AGU with a bit more time to spare than on Monday!

I ran a few more migrations at the beginning of the week, but they were still not very satisfying so Rufus recommended that I just move onto S-waves rather than worry too much about it. As I mentioned last week, the velocity model has to be perfect and we just didn’t get data deep enough to make any solid conclusions about the model at depth. So in the abstract, I left it at stacking. Perhaps, once I’m back at school, we’ll be able to look at the migrations again and possibly get them worked out, but in the meantime I’m just not worrying about them. So, instead, I started looking at S-waves. With four days left here (my last day is on Thursday), I doubt I’ll get anywhere close to finishing them, but at least I can have them set up so someone here at the office can get right into picking, and not have to worry about pre-processing, once I’m gone. The analysis steps for S-waves are similar to P-waves, but slightly more complicated and immensely more tedious. Instead of 135 old FFIDs (original shots), I now have 489 (it’s still 118 channels, but we took at least 4 shots at each geophone). Like with P-waves, I had to create fake shot files and input a fake geometry (though this time actually based on all 118 channels, instead of 60 like with P-wave fake geometry) into Promax. I then had to create multiple log files to also input into Promax that used the field notes to label which shots were bad, which had to be stacked, and which were skipped. I also had to keep track of when the direction we were hitting the block changed in each set of points so I could then reverse the polarity of half the shots on Promax, so they all had the same polarity when I stacked them. Now I’m just in the process of checking through all 489 shots to find bad traces, as well as shots that look out of place in each set. Needless to say it’s going to take me a bit longer than it did for P-waves! Then I’ll have to really stack everything on Promax and shift all the shot points up, like I did with P-waves, and then I’ll be ready to pick, which given how noisy the data is, should be another challenge to look forward to this week.

On Sunday though, we had a slight change of pace and went back out to do some fieldwork. I’ll admit, being at work at 7am on a Sunday wasn’t great, but it was nice to get out into the field again, even if this time we were going to a dump! The fieldwork took place at a landfill on the East Bay and took us all day. Apparently the landfill is slowly slipping into the bay (all that sits between it and the bay is a salt marsh that I believe is also a wildlife refuge). So a geotechnical company is going to put in a metal wall to act as a levee between the dump and the bay. But first they want a survey done to get a sense of what the subsurface looks like. We ran a 300m line along the edge of the landfill and then a 60m line, perpendicular to that, up a steep slope of mulch that undoubtedly overlain trash. However, being right next to the marsh and the bay, the view was really nice and the smell was completely bearable. Besides having to dig through two feet of mulch on the hill to actually reach dirt, it was a nice afternoon and we were able to get done pretty quickly. It was a nice way to spend my last weekend before I finish up work here!